[Pseudohyperkalemia of erythrocyte origin. Passive increase of membrane permeability to potassium].

The pseudo-hyperkalemia is a biochemical abnormality suspected when the blood level of K is increased, contrasting with the absence of usual symptoms of hyperkalemia. The diagnosis is confirmed by the discrepancy between K+ blood levels which are normal if measured immediately after the blood sample is drawn, and increased if the blood sample is incubated at the room temperature. In our case, the pseudo-hyperkalemia is due to the passage of K outside the erythrocytes by an increased passive membrane permeability to K. In vivo, this increased passive outflow of K seems to be compensated by an increased active inflow of K dependent of the sodium pump. Therefore is explained, the absence of true hyperkalemia and clinical symptoms. In vitro, it seems that the sodium pump is no longer able to assure this increased activity. Therefore the abnormality appears as a late increase of kalemia.